The present invention relates to a bracket for correcting dentition, which is made of polycarbonate, and further relates to a bracket for correcting dentition, of which adhesivity to a plastically deformable synthetic resin layer bonded to the bracket, is enhanced.
A bracket for correcting dentition is a device for correcting dentition by fitting and fixing it directly to a tooth in combination use of a wire.
Many of conventional brackets used for correcting dentition are those made of metals, but from a point that deformation occurs by a lengthy use and also from the viewpoint of their weight, synthetic resin brackets are replacing them. As the synthetic resins, polycarbonate is most suitable from a point that a high strength, staining resistance and high water resistance are required.
However, bonding of polycarbonate is difficult, and suitable non-toxic adhesives imparting a high adhesive strength are very few. Therefore necessary adhesive strength is furnished by physical methods, such as roughening of a bond surface of the bracket and fitting of a metal net to the bottom surface of the bracket (Japanese Patent Publication Kokai No. 2-265541).
Also the bracket is small (about 3 to about 4 mm square), so skill is required in fixing it and adjusting a position of it. In order to make it easy to set the position of the bracket and fix it, there was developed a method to bond a plastically deformable photocuring synthetic resin layer (also referred to as a base plate) to the bottom surface of the bracket through an adhesive layer interposed therebetween and fix the base plate to the tooth after or at the same time when the shape conforming to a direction and surface condition of the tooth is obtained (Japanese Patent Publication Kokai No. 5-269147).
Also in this bonding of the base plate and bracket, there still occurs the above-mentioned problem of the adhesion failure in polycarbonate.